SOFIA, May 7 (Reuters) - The IBF's mandatory challenger Kubrat Pulev's representative said on Thursday that the world heavyweight title fight against Briton Anthony Joshua could take place in front of a crowd at a Roman Amphitheatre in Croatia.

The 38-year-old Bulgarian, a former European amateur super-heavyweight champion, was due to meet Joshua at the Tottenham Hotspur Stadium in London on June 20 but the fight was put on hold because of the COVID-19 pandemic.

Last week the British Boxing Board of Control (BBBofC) said it hoped professional boxing could resume in July without spectators but promoter Eddie Hearn said Joshua would fight behind closed doors only as a "last resort".

"We have given ourselves (the two camps) four weeks to look for a new territory if the situation and measures in England do not change," Pulev's manager Ivaylo Gotsev told local media after discussing the matter with Joshua's camp.

"We are discussing Croatia, there is a unique Roman stadium - Pula Arena, there and we are in active talks," he said, adding that the fight would most probably take place in August or September.

The Roman Amphitheatre in the northern Adriatic city of Pula is well-known for hosting concerts of top class artists such as Luciano Pavarotti, Sting and Elton John. Two ice hockey games were played there in 2012.

"We like this option because it is in Europe, in the middle of the continent," Gotsev said. "The arena itself predisposes to an unprecedented event in our time. There will also be an opportunity for spectators with the right measures taken.

"There needs to be a mutual agreement. We want the terms and conditions to be beneficial for both parties.

"They can't meet in Bulgaria because Joshua will not agree. He wanted to fight at home but force majeure brought a change. Kubrat, however, was ready to fight in Joshua's backyard, even if the judges were his family."

The 30-year-old Joshua reclaimed the WBA, WBO and IBF belts with a unanimous points win over Mexican-American Andy Ruiz Jr in Saudi Arabia in December.

Joshua was initially due to fight Pulev at Cardiff's Principality Stadium in October 2017 but the Bulgarian, known as "The Cobra", withdrew after suffering a shoulder injury in sparring.

Pulev, one of Bulgaria's most popular sportsmen, challenged for the IBF world heavyweight title in 2014, losing to Wladimir Klitschko in Hamburg on a fifth-round knockout. (Reporting by Angel Krasimirov Editing by Christian Radnedge)